Use of olefin polymer oil for grease manufacture



Patented Oct. 24, 1950 USE OF OLEFIN POLYMER OIL FOR GREASE DIANUFACTURE William B. Whitney, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of Delaware No Drawing. Application May 4, 1948, Serial No. 25,097

Claims.

This invention relates to improved lubricants. In one of its more specific aspects it relates to olefin polymer lubricants. In another of its more specific aspects it relates to a mono-olefin polymer grease having high consistency and high work stability.

Conventional greases, in general, comprise a petroleum hydrocarbon lubricating oil in which a metal salt of a fatty acid is dispersed to such a degree as will give the resulting grease the desired consistency. Dispersion of metal salt or soap in the lubricating oil varies greatly from the rough, long-fiber, soda-bas greases through the calciumand aluminum-base greases to greases such as lithium and certain anhydrous sodium base greases. The extent of dispersion of soap in oil depends upon many variables. Among those variables which help determine the extent of dispersion are the presence of glycerine or water, the metal from which the soap is derived, the fatty acid radicals from which the soap is derived, the process of preparing the grease, and the properties of lubricating oil used.

I have found that, while there are many factors which affect the interaction of an oil and a given soap, most of the physical constants which measure these factors do not correlate with the observed behavior of the properties of the grease. Viscosity index, specific dispersion, refractive index, and density of an oil are very poor indicators of the behavior of soap and oil when they have been heated sufficiently to cause mutual solubility, cooled suddenly to form a gel, and worked to a smooth grease. While the abovementioned physical properties do have an influence, I have found that viscosity has a considerably greater influence than do the others. Sodium stearate may, for example, be dispersed readily in petroleum oil fractions having a viscosity of less than approximately 400 Saybolt Universal seconds at 100 F. but may be only slightly dispersed in petroleum oil fractions having appreciably higher viscosities. Lithium stearate, on the other hand, appears to be dispersable in practically all oils, whereas lithium laurate appears to be limited, as regards satisfactory dispersion, to oils having viscosities not greater than 532 Saybolt at 100 F. In order that a grease may be obtained from an oil and a soap, the soap must have a solubility in the oil within certain limits. If the soap is insufficiently soluble, no grease is formed, but instead, a suspension of solid soap in oil is obtained. If the soap is too soluble, a liquid solution of soap in oil is obtained. Thus a certain range of partial solubility is necessary.

An object of this invention is to provide an improved grease having relatively high consistency. Another object of the invention is to provide a grease having high work stability. An-

other object of the invention is to provide a soap dispersion medium which gives improved properties of consistency to a finished grease produced therewith. Another object of the invention is to provide an aliphatic mono-olefinic polymer grease having relatively high consistenc during extended working periods. Another object is to provide an improved method of preparing greases. Other and further objects and advantages of the invention will be apparent upon consideration of the accompanying disclosure.

I have found that aliphatic polymers of monoolefins, preferably those olefins having from three to five carbon atoms per molecule, may be better utilized as a dispersion medium for metal salts of a fatty acid for the formation of a. grease than petroleum lubricating oil fractions. Actually, aliphatic polymers of mono-olefins may be used in some cases when the viscosity of the polymer oil falls at the extreme limits of a viscosity range between 25 and 20,000 Saybolt Universal seconds at 100 F. It is preferred, however, in the production of greases of this invention to utilize those polymers having viscosities from about 35 to about 500 Saybolt Universal seconds at 100 F. Greases prepared by the dispersion of a metal salt of a fatty acid in polymers of this type have relatively high consistency and high work stability.

Aliphatic polymers of mono-olefins, such as are described above, may be prepared by polymerizing at least one olefin, preferably selected from those having from three to five carbon atoms per molecule, in the presence of a tetrahalide of a group IV element having an atomic number within the range of from 14 to 50, inclusive. Selected olefins may be reacted in the presence of such a tetrahalide during agitation of the reactant materials at a temperature of between F. and 500 F. The exact conditions for such a reaction may be varied depending upon the catalyst and upon the olefin used. It is preferred in such a reaction to use a temperature of between F. and to 200 F. Polymerization of olefins in the presence of the above disclosed catalysts is relatively easy to control. The polymer product of a reaction under these conditions is relatively free of undesirable by-products, such as tar and other heavy deleterious materials. If desired, the reaction products may be washed, dried, and given a light clay treatment. The products may then be distilled to recover those polymers boiling in the desired boiling range. Use of the tetrachloride of titanium, silicon, germanium, or tin is especially advantageous for the production of polymers in continuous processes, since these tetrachlorides are normally liquid. Zirconium tetrachloride is also used very advantageously as a polymerization catalyst.

Selected metal salts of fatty acids having between twelve and twenty-four carbon atoms per molecule may be incorporated in selected polymers prepared as above described so as to produce the highly desirable grease. It is preferred to use metal salts of fatty acids which have a carbon content of from fourteen to twenty carbon atoms per molecule. Generally between 5 and 70 per cent by weight of a soap of a fatty acid may be incorporated in a polymer of the type above described at a temperature between about 150 F. and about 500 1''. It is preferred, however, to incorporate between and 50 per cent by weight of a soap of a fatty acid in a polymer of the type described. Such a mixture of a properly selected metal salt and polymer will when cooled, preferably at a rapid rate, form a gel.

The fatty acid used in making the metal salt should be relatively pure. By the term "relatively pure." it is meant to employ a single fatty acid, for example, stearic acid. If a. mixture of fatty acids is used, they should be very similar in chemical structure and number of carbon atoms per molecule, for example, a mixture of a straightchain Cu acid with a straight-chain Cm acid. Another important factor in producing suitable greases is that the metal salt should be neutral and contain substantially no free fatty acid.

The temperature below which the grease should be cooled is that at which solidification from a liquid to a gel occurs. This temperature is definite and possibly related to the crystalline or colloidal structure of the metal salt. At least, it is a characteristic of the soap-oil mixture, It is not intended that the temperature to which the mixture is cooled should be limited to any specified temperature, so long as it is below the gelation temperature. It is desired, however, that the time of cooling be as short as possible, generally within a period 0! from 10 to 600 seconds. Longer periods of time may be used for cooling these mixtures if desired. but it is preferred to cool the heated mixture to a gel within a period of from 10 to 300 seconds. The cooled grease may be worked in any conventional grease worker to obtain the desired consistency. v

Sodium, lithium, calcium, and aluminum salts of fatty acids are among thosemetal salts which may be utilized in greases of this invention. Other metal salts may, however, be utilized to advantage in the preparation or such greases.

The advantages of this invention are even more apparent upon examination of the following example. The specific reactants and specific conditions of reaction are presented as being typical and should not be construed to limit the invention unduly.

Example A suspension of 450 grams of zirconium tetrachloride in normal pentane was charged to a reactor. The suspension was raised to a temperature of about F. Propylene was slowly added -to the suspension and intimate contact was maintained between the propylene and the zirconium tetrachloride by agitation of the mixture. The temperature of the reaction was maintained between 100 F. and 154 F. Polymer material resulting from the reaction was washed, dried, and given a light clay treatment. A first polymer fraction. 1. e., that polymer material lighter than SAE-IO lubricant material was obtained by distillation of the polymer product in a continuous vacuum still at about 455 F. and 20 mm. pressure. Approximately 30% of the total polymer product was obtained in that cut. A second fraction, i. e., that polymer material in the viscosity range of SAE 10 to 30 lubricant material was obtained at about 705 F. and 0.1-0.15 mm. pressure. Polymers heavier than SAE 30 lubricant material comprised the distillation residue or third fraction.

Characteristics of the second fraction are set forth below.

Certain of the properties of the first and third polymer fractions together with five petroleum oil fractions are set forth below in Table II.

Table II Vls. SUS Vis. SUS at 100 F. at 210 F.

is:I Olaiin polymer trac- Petroleum fraction B; 183. 2 44. 6 91 1.4748 3. Petroleum fraction 0. 283. 5 50. 9 93 l. 4805 0. 87(1) 3rd Olefin polymer fraction D 16, 555 294. 6 33 l. 4746 0. 8568 Petroleum fraction E 11, 531 237. 0 29 1. $88 0. 9554 Petroleum traction F. 2, 252 US. l 68 l. 5224 0. 9368 Petroleum fraction G. 532. 7 63. 03 87 i. 4921 0. 8888 An attempt was made to disperse 20 per cent by weight of sodium stearate in each of the lubricant fractions set forth in Table II above. The mixture of metal salt and lubricant was heated until mutual solubility occurred or until the mixture reached a temperature of about 500 F. The mixture was then cooled rapidly and worked in an ASTM grease worker (Precision Scientific Motormatic Model) as described in ASTM Test D-2l'l-44T. The consistency and work stability of resulting greases is set forth below in Table 111.

Table III Oil A Oil B Oil C Oil D Oil E Oil F Oil 0 Strokes of Working 12. 33? Petroleum Petroleum $2 852? Petroleum Petroleum Petroleum Fraction Fraction Fraction Fraction Fraction Fraction Fraction No grease. No grease. 221 (l Sodium stearate may readily be dispersed in petroleum oil fractions having viscosities of less than approximately 400 SUS at 100 F. Petroleum fractionsB and C fall within that category. Examination of th consistency and work stability results of greases prepared from those two petroleum fractions discloses a relatively high-consistency grease. Sodium stearate is not, however, generally dispersable in petroleum fractions having viscosities appreciably higher than 400 SUS at 100 F. Petroleum fractions E, F, and G fall within that category. Examination of Table III discloses that it was not possible' to prepare a grease from petroleum fractions E and F and the grease prepared from petroleum fraction G had a relatively low consistency. The viscosity of the olefin polymer fractions completely bracketed the petroleum fraction viscosities. Olefin polymer fraction A had a viscosity of 39.1 SUS at 100 F. The grease prepared from that olefin polymer fraction had a relatively low consistency after 2000 strokes of the grease worker but after 10,000 strokes the grease had taken on a relatively high consistency and had excellent work stability. Olefin polymer fraction D was comparable in viscosity to the petroleum fractions at the upper end of the viscosity range, since it had a viscosity of 16,655 SUS at 100 F. The grease prepared with this olefin polymer fraction was softer than that prepared from petroleum fractions B and C and that prepared from olefin polymer fraction A. It did, however, have a satisfactory consistency and improved after working with a grease worker for 100,000 strokes. It is believed that examination of the above examples indicates very definite advantages to be derived by the preparation of a grease with olefin polymers as has been above described.

As will be evident to those skilled in the art, various modifications of this invention can be made or followed in the light of the foregoing disclosure and discussion without departing from the spirit or scope of the disclosure or from the scope of the claims.

I claim:

1. An improved lubricant comprising essentially between 30 and 95 per cent by weight 01' at least one polymer, in the viscosity range above 'SAE 30 lubricant to 20,000 SUS at 100 F'., produced by treating at least one aliphatic monoolefin having between three and five carbon atoms per molecule with a tetrahalide of a group IV element having an atomic number between 14 and 50 under polymerization conditions; and between 5 and 70 per cent by weight of a soap of a fatty acid selected from the group consisting of sodium, lithium, calcium, and aluminum soaps.

2. The lubricant of claim 1, wherein said soap s a sodium soap.

3. The lubricant of claim 1, wherein said soap is a lithium soap.

4. An improved lubricant comprising essentially between 30 and 95 per cent by weight of at least one polymer, in the viscosity range above SAE 30 lubricant to 20,000 SUS at 100 F., produced by treating at least one aliphatic mono-olefin having between three and five carbon atoms per molecule with zirconium tetrachloride under polymerization conditions; and between 5 and 70 per cent by weight 01 a soap of a fatty acid selected from the group consisting of sodium, lithium, calcium, and aluminum soaps.

5. An improved lubricant grease consisting 01' between 50 and per cent by weight of a polymer, in the viscosity range above SAE 30 lubricant to 20,000 SUS at F., produced by treating an aliphatic mono-olefin having three carbon atoms per molecule with a tetrahalide of a group IV element having at atomic number between 14 and 50 under polymerization conditions; and between 15 and 50 per cent by weight of a soap of a fatty acid selected from the group consisting of sodium, lithium, calcium, and aluminum soaps.

6. The lubricant of claim 5, wherein said aliphatic mono-olefin is propylene; and said soap is sodium stearate.

7. An improved lubricant grease consisting of between 50 and 85 per cent by weight of a polymer, having a viscosity of 16,555 SUS at 100 F., produced by treating propylene with zirconium tetrachloride under polymerization conditions; and between 15 and 50 per cent by weight of sodium stearate.

8. An improved lubricant grease consisting of between 50 and 85 per cent by weight of a polymer, in the viscosity range above SAE 30 lubricant to 20,000 SUS at 100 F., produced by treating an aliphatic mono-olefin having four carbon atoms per molecule with a tetrahalide of a group IV element having an atomic number between 14 and 50 under polymerization conditions; and between 15 and 50 per cent by weight of a soap of a fatty acid selected from the group consisting of sodium, lithium, calcium, and aluminum soaps.

9. An improved lubricant grease consisting of between 50 and 85 per cent by weight of a polymer, in the viscosity range above SAE 30 lubricant to 20,000 SUS at 100 F., produced by treating an aliphatic mono-olefin having five carbon atoms per molecule with a tetrahalide of a group IV element having an atomic numbe between 14 and 50 under polymerization conditions; and between 15 and 50 per cent by weight of a soa of a fatty acid selected from the group consistin of sodium, lithium, calcium, and aluminum soaps.

10. An improved lubricant grease consisting of between 50 and 85 per cent by weight of a polymer, in the viscosity range between 16,555 and 20,000 SUS at 100 F., produced by treating an aliphatic mono-olefin having between three and five carbon atoms per molecule with a tetrahalide of a group IV element having an atomic number between 14 and 50 under polymerization conditions; and between 15 and 50 per cent by weight of a soap of a fatty acid selected from the group consisting of sodium, lithium, calcium, and aluminum soaps.

WILLIAM B. WHITNEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain June 25, 1937 

1. AN IMPROVED LUBRICANT COMPRISING ESSENTIALLY BETWEEN 30 AND 95 PER CENT BY WEIGHT OF AT LEAST ONE POLYMER, IN THE VISCOSITY RANGE ABOVE SAE 30 LUBRICANT TO 20,000 SUS AT 100*F., PRODUCED BY TREATING AT LEAST ONE ALIPHATIC MONOOLEFIN HAVING BETWEEN THREE AND FIVE CARBON ATOMS PER MOLECULE WITH A TETRAHALIDE OF A GROUP IV ELEMENT HAVING AN ATOMIC NUMBER BETWEEN 14 AND 50 UNDER POLYMERIZATION CONDITIONS; AND BETWEEN 5 AND 70 PER CENT BY WEIGHT OF A SOAP OF A FATTY ACID SELECTED FROM THE GROUP CONSISTING OF SODIUM, LITHIUM, CALCIUM, AND ALUMINUM SOAPS. 